1. Field of the Invention
This invention generally relates to apparatus for removing and transporting articles from molds. More specifically, the present invention relates to such apparatus that is very well suited for carrying the articles, in a very short period of time, away from the molds and depositing the articles for further processing in a high speed, automated production system.
2. Description of the Prior Art
Recently, attention has been directed toward forming contact lenses in an automated molding system. In such a system, each lens is formed by sandwiching a monomer between front and back mold sections. The monomer is polymerized to form a lens, which is then removed from the mold sections, further treated and then packaged for consumer use.
The mold sections used in the above-outlined process may themselves be formed in injection molding or compression molding processes. These mold sections may be made from the family of thermoplastics, for example polystyrene, which is an excellent material for making these mold sections. Polystyrene does not chemically react with the hydrophilic material used to make the contact lens, therefore, very high quality contact lenses may be formed in polystyrene molds. In addition, polystyrene is widely available and relatively inexpensive. Because of the ease and low cost with which polystyrene mold sections may be made and then used to mold contact lenses, each pair of polystyrene mold sections typically is used to mold only one contact lens and is then disposed of.
In the above-discussed automated contact lens production system, it is desirable to eliminate or to minimize any exposure of the hydrophilic monomer to oxygen. Correspondingly, it is desirable to eliminate or minimize the exposure of the lens mold sections to oxygen. Therefore, when polystyrene mold sections are made and then used in the above-discussed manner, it is desirable to transfer these mold sections quickly from the mold in which they are made, to a low oxygen (preferably nitrogen) environment. It is difficult to achieve the desired transfer speed with conventional robot assemblies or controls because presently available robots do not move fast enough and precise enough to get in and out of the mold with the desired speed. In particular, if these robots are moved with the necessary speed, they tend to waffle and shake undesirably as they come to a sudden stop, and the movements of the robot are not sufficiently precise. If the robots are slowed down to move more precisely, the robots no longer have the desired speed.
Also, in the above-mentioned automated contact lens production system, the contest lens mold sections may not be fully solidified when they are ejected from the mold in which they are made. It is, therefore, important that any robot or apparatus which is used to carry the lens mold sections away from that mold not interfere with the desired optical qualities of the contact lens mold sections. In particular, it is important that any such robot or apparatus absorb the energy of the lens mold sections as they are transferred to that robot or apparatus without altering the shape, form or dimensions of the lens mold sections. That robot or apparatus must, likewise, be able to carry the lens mold sections in a manner that permits those lens mold sections to cool and completely harden in the desired manner.
In addition, in order to maximize the optical quality of the contact lenses, it is preferred that the optical surfaces of the polystyrene mold sections--that is, the surfaces of those mold sections that touch or lie against the hydrophilic monomer as the lens preform is being molded--not be engaged or touched by any mechanical handling equipment, as the mold sections are transported and positioned in the lens molding system.